To do this, IceCube used two tricks.
Second, it used a very thick absorber - the Earth. With this, the measurement was quite simple. It Compared to a baseline of near-horizontal neutrinos that traversed only a relatively small amount of matter, energetic near-vertical neutrinos were absorbed going through the Earth. The figure above shows the predicted transmission probability (= 1 - absorption probability), as a function of neutrino energy and zenith angle; the latter shows how much Earth matter was traversed.
There are of course many complications - experimental uncertainties on the neutrino energy, neutral current interactions, where a neutrino may emerge from the Earth with a lower energy than it entered, modelling the material within the Earth, etc., but the result clearly showed that neutrinos are absorbed at about the expected rate. More precisely, the best-fit cross-section was. 1.3 +/- 0.5 times the predictions of the Standard model where I have combined the statistical and systematic uncertainty. It was not trivial to find a good definition for the neutrino energy range for which this measurement applies, because different methods give somewhat different energy ranges, but we settled on a method that returned a range from 6.3 TeV to 980 TeV. For comparison, the highest energy measurements at an accelerator laboratory only reached 0.37 TeV - our measurement reaches order of magnitude higher energies than than. The figure below puts this in perspective, comparing our measurement with the previous accelerator work. The cross-sections (y axis) are divided by the neutrino energy so that everything fits on the graph better; otherwise, it would span many orders of magnitude.
I have to mention that this was the dissertation work of my (now graduated) graduate student, Sandra Miarecki. Sandy had a very interesting preparation for graduate school - she was a career US Air Force Pilot, serving many roles, including as a test pilot, before retiring from the Air Force and coming to graduate school in Berkeley. After graduate school, she became an Assistant professor at the US Air Force Academy. The LBNL news center has a very nice article about her.
The Nature article also recieved a fair amount of press coverage. I will just mention one article, in Symmetry magazine, which goes into more detail about the analysis than other press writeups.
I think neutrinos can be used in the late 2020s to image grains of Uranium on Earth . The idea is to place single radiowave or microwave detectors inside a captured comet. The comet has been brought L4 or L5. The rim around Earth's globe, looking away from the Sun, will emit neutrinos only from the crust and above. These neutrinos will interact with ice inside a comet and produce radiowaves and microwaves. These neutrinos will have originated from a cylinder around 150km deep and I'm hoping centimeters in diameter. After one rotation of Earth, there will be a second subsequent shower of microwaves and/or radiowaves and the location of the Uranium's elevation and surface speck will be triangulated as a slightly different comet interior shower will be produced. There are trillions of such detectors placed in the comet and they are transparent to the wavelength measured. Too long a wavelength and you have GPR ringing as the radiowaves reflect of the sublimated comet microcrystals 2 or 3 metres beneath the surface; the idea is for many detections to be directional so an arrow at Earth can be reconstructed.
ReplyDeleteThis has geopolitical implications but Uranium is a long term vulnerability.
I've figured out more details. Cherenkov radiation through ice creates a cone of microwaves just as it creates a cone of blue light. The cone is weaker and shaped a little differently. I'll use the technique of transmitting images through parallel conductive rods. Microwaves at the source create a near field. One microwave may not effectively be imaged by one Pb (or whatever material) rod but 4 or 40 microwaves should be imagible along parallel rods. Somehow the rods are connected to a near field detector at the far end of the comet. The strength of the near field signal gives the location of the impact as well as the Uranium source on Earth. This will work on Earth too aimed at Fukushima or wherever.
ReplyDeleteI have a method to locate nuclear materials. Microwaves form a Cherenkov light cone after a neutrino impacts ice. These microwaves will travel along a “wire medium lens”. A cylinder of ice faces Earth or a nuclear materials location. This is followed by an Aztec Pyramid lens with the wide end facing the ice. Microwaves will travel from the ice to the fat end of the pyramid. After the narrow end of the pyramid are microwave sensors. The microwaves will be focused enough to be detected. Two neutrinos from a nuclear source, impacting the ice at different locations, will form microwave cones that can be used to triangulate exactly where the uranium is. This will scale from comets to local detectors. It suggests the Navy should go battery with tidal energy recharging, and that nuclear materials should be stored at Australia and guarded until better heavy lift is available.
ReplyDeleteThis is a directional neutrino detector procedure that should be good enough for spotting leaky wet storage containers. With better microwave sensors around the corner, it will eventually offer real time location data of nuclear materials, though ice cooling or changing is not good in many locales.:
ReplyDeletea wire medium super lens is dumped in water an a rectangular ice prism is made. At 100 metres, the microwave diffraction Cherenkov Cone of nuclear material in a long term storage tank is maybe 2-3 metres above a leak in the ground. That is about 3 degrees difference for average neutrino light cone overlap. Underground, the ice block with the wire medium superlens is tilted so the wire face is at 56-59 degrees and only the 3 degrees of single leak source illuminates a cumulative plastic sensor grid placed along the fair field side (facing tilted up)of the superlens. Microwave Cherenkov Cones are diffuse and maybe a ring, so if there is too much overlap this will fail. Mobile detectors are trickier with the mantle. I hope someone else will figure out how to make this work underground and I think geo-neutrinos have a "brighter" future than do others.
The above system is good for trying to catch with NPP a spaceship running away as well. My main fear was latent robots burrowing in granite and coming up with a winning strategy before we can detect them. Quantum entangled microwaves can penetrate soil and sand but not the iron in granite; maybe 6 meters. A GPR hole network needs to be every 100m and is difficult to lay down where the X-men hid.
ReplyDelete100000x cheaper is to entangle maybe a million oxygen molecules/atoms in a line. A neutrino flying through all of them will slightly decohere them. If they are aligned along an optical waveguide and arranged properly, they should move slightly in a way that is detectable by a laser.
...Eerkens postulates a neutrino will stimulate a photon of a laser and a lined up laser will emit two opposite direction neutrinos instead of a photon at transition energy de-excitation every 1/10 million instances. I don't understand the flux equation that determines how often the 2nd laser emits a photon when subject to a neutrino from the first laser.
ReplyDeleteTo apply it to a subsurface cave detector in 5 years, geoneutrinos emit at a line of (one million?) entangled quantum dot lasers placed in granite. This requires diamond instrumentation. The geoneutrino triggers the flux equation and quantum dot laser emissions (reflected parallel to the line of dots and to the front) at a rate much more than 1/10 million events per neutrino. The geoneutrino flavor oscillation rates are affected by a cave; I assume they oscillate less given less iron on the way to the dots detector. If the neutrino undulation frequency must match the laser transition nrg frequency, only a fraction of geoneutrinos will have the energy to trigger the dots lasers. The quantum dots frequency is set just above or below what triggers the lasers and decoheres the dots. This generates a 3d GIS map of caverns in the lithosphere and a way to quickly re-entangle the dots needs to be found.
The entangled quantum dots are not likely for a decade or more; would be magnetically aligned or in a nanotube. But I have a solution that should work. It rests upon transparent quantum dots. There is a mineral and aquifer application that might cause someone to patent it, so I can't blog it or I'm stuck with Musk's administrative duties in only going after profitable technologies.
ReplyDeleteI want to to thank you for this wonderful read!! I definitely loved every bit of it. I have got you bookmarked to check out new things you post
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